Continuous curing and post curing apparatus

ABSTRACT

An apparatus for continuous curing of a plurality of extruded strands can include a rigid frame structure formed by interconnecting a plurality of rigid frame members. A rigid top plate member and a rigid bottom plate member are attached to the rigid frame structure. A plurality of upper spindle units is rotatably attached to the rigid top plate member and a plurality of lower spindle units is rotatably attached to the rigid bottom plate member. A pair of drive motors is attached to the rigid frame structure. A gear assembly attached to the rigid frame structure is operably engaged to the pair of drive motors and a chamber is supported on the rigid frame structure for curing the plurality of extruded strands. The pair of drive motors drives the gear assembly to continuously pass the plurality of extruded strands through the chamber for continuous curing and post-curing.

REFERENCE TO RELATED APPLICATION

This application claims priority of U.S. Provisional Patent ApplicationSer. No. 61/476,220, which was filed on Apr. 15, 2011. The subjectmatter of the earlier filed application is hereby incorporated byreference.

BACKGROUND OF THE EMBODIMENT

1. Technical Field of the Embodiment

The present embodiment relates in general to a method and apparatus forthe continuous curing and post curing of strands of extruded rubberproducts and the like. More specifically, the present embodiment relatesto a method and apparatus that can continuously perform both curingand/or post curing processes of strands of extruded rubber and similarproducts.

2. Description of the Related Art

Several types of apparatuses and methods are employed for the continuouscuring of longitudinally extruded strands of rubber and similarproducts. Conventional apparatuses offer discontinuous or batchprocesses for curing rubber and related extruded strands. Theconventional apparatus and methods typically cure continuous lengths ofextruded strands in a continuous fashion in a liquid salt bath or curingoven with heat and/or through a microwave process, and are thenpost-cured in a batch fashion where the extrudate is cut and post-curedin an oven or autoclave. The conventional method of batch post-curing isinefficient due to the presence of multiple manufacturing processes,increased labor, and resulting overhead expenses.

Various apparatuses and methods exist for the curing of different typesof materials. U.S. Pat. No. 4,155,695 issued to Karppo on May 22, 1979discloses an apparatus for continuous curing of elongated products, suchas cables comprising a conductor surrounded by a mantle of crosslinkable material. The cable is passed longitudinally through a curingtube for heating the cable to a curing temperature and subsequentlysubjected to cooling. The heating of the cable in the heating zone iscarried out by means of heat radiation in a pressurized gas atmosphereand the cooling of the cable is carried out in the presence of a gasunder pressure so that heat is transferred from the heated cable in thecooling zone partially by radiation to the cooled wall of the tube andpartly by convection to said cooled gas.

U.S. Pat. No. 4,356,143 issued to Hill on Oct. 26, 1982 discloses anapparatus and a method for the curing of a continuous length of curablematerial. The length of material is passed through a curing chamberdefined by a tubular body. This tubular body is disposed in the upperpart of another heated tubular body which contains a heat exchangeliquid. This liquid is fed to one or more injectors disposed at one orboth ends of the body, injected along the chamber, and then allowed todrain back into the body. The body contains a farther tubular bodydownstream of, and partitioned from, the original tubular body. Thetubular body also has an injector through which water is injected tocool the length of material. The tubular body may be provided with drainholes through which heat exchange liquid can be quickly drained at theend of a curing run. It may also be provided with air vents or alongitudinal slot in its upper part to release trapped air. Devices forwiping heat exchange liquid clinging to the cured material on emergencefrom the curing chamber are also provided.

The above conventional apparatuses and methods employ batch processingof the extrudate in the cooling zone, and uses pressurized hot air orother gas in the heating zone. Generally these conventional apparatusesand methods cure in a continuous fashion in a liquid salt bath or curingoven with heat and/or microwaves; and are then post-cured in a batchfashion where the extrudate is cut and post-cured in an oven orautoclave. These methods cannot be employed for the simultaneous andcontinuous curing of multiple strands of the extrudate.

Hence, it can be seen that there is a need for an improved method andapparatus for the continuous curing of extrudates. Continuous curing ispreferred to the discontinuous curing processes because the quality ofthe final product is higher due to the ability to accommodate longerextrudates and easier quality control. The continuous curing method isalso more economical due to the presence of high speed lines and theabsence of the need for the intermediate conveying of the extrudate.Lower overall costs as a result of less manpower, less spacerequirements, and lower energy requirements are additional benefitsrealized as a result of using the continuous curing method andapparatus.

SUMMARY OF THE INVENTION

The present invention may satisfy one or more of the above-mentioneddesirable features. Other features and/or advantages may become apparentfrom the description which follows.

The present invention provides an apparatus for continuous curing of aplurality of extruded strands. The apparatus comprises a rigid framestructure formed by interconnecting a plurality of rigid frame membershaving a top portion, a bottom portion, side portions, a front portionand a rear portion. A rigid top plate member is attached to an upperpart of the front portion and a rigid bottom plate member is attached toa lower part of the front portion. A plurality of upper spindle units isrotatably attached to the rigid top plate member and a plurality oflower spindle units is rotatably attached to the rigid bottom platemember. A pair of drive motors is attached to the rigid frame structure.A gear assembly attached to the rigid frame structure is operablyengaged to the pair of drive motors and a chamber is supported on therigid frame structure for curing the plurality of extruded strands. Thepair of drive motors drives the gear assembly to continuously pass theplurality of extruded strands through the chamber for continuous curingand post-curing.

Multiple lines of the plurality of extruded strands are passed throughthe free spinning roller and the driven roller of each of the pluralityof spindle units. The plurality of extruded strands is wrapped aroundthe free spinning roller and the driven roller. The pair of drive motorsis employed for rotating the plurality of spindle units. The pluralityof extruded strands is allowed to pass through a dual function chamberfor heating/cooling at a speed determined by the speed of the pair ofdrive motors. The plurality of extruded strands is allowed to remain ina heat/cool zone exerted by the dual function chamber for apredetermined period of time. This makes a continuous process of curingof the plurality of extruded strands.

The apparatus and method cures and post-cures extrudate by the method ofhigh velocity heat or forced-air convection concentrated around theextrudate and also can cool the extrudate in the same fashion as heatingit via heat-exchange coils in the passage way of the forced airconvection where the forced air is passed through the fined coils of theheat exchanger and closed looped refrigeration is passed through thefined coils to chill the forced air to a desired temperature. Thisapparatus and method also de-humidifies the extrudate by sensing thehumidity within a forced air convection chamber and when there is toomuch humidity the apparatus calls for low dew-point air that is injectedinto the forced air convection chamber and vents out the most humid airbased on the location of the vent(s) in the system and lowers thehumidity to a desired level which in turn lowers the humidity of theproduct.

BRIEF DESCRIPTION OF THE DRAWINGS

Elements in the figures have not necessarily been drawn to scale inorder to enhance their clarity and improve understanding of thesevarious elements and embodiments of the invention. Furthermore, elementsthat are known to be common and well understood to those in the industryare not depicted in order to provide a clear view of the variousembodiments of the invention, thus the drawings are generalized in formin the interest of clarity and conciseness. The skilled artisan willunderstand that the drawings described below are for illustrativepurposes only. The drawings are not intended to limit the scope of thepresent teachings in any way.

FIG. 1 is a front view of an apparatus in use for continuous curing of aplurality of extruded strands in accordance with the present teachings;

FIG. 2 illustrates a front view of the apparatus for continuous curingof the plurality of extruded strands in accordance with the presentteachings;

FIG. 3 illustrates a perspective view of a rigid top plate membershowing a plurality of upper spindle units strands in accordance withthe present teachings;

FIG. 4 illustrates a perspective view of the apparatus showing a pair ofpair of drive motors, a top gear box and a bottom gear box in accordancewith the present teachings;

FIG. 5 illustrates an exploded view of a dual spindle and a centralshaft assembly in accordance with the present teachings;

FIG. 6 illustrates a perspective view of the apparatus for continuouscuring of the plurality of extruded strands in accordance with thepresent teachings; and

FIG. 7 illustrates the operational flow chart of a method for continuouscuring and post-curing of the plurality of extruded strands utilizingthe apparatus in accordance with the preferred embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE VARIOUS EMBODIMENTS

In the following discussion that addresses a number of embodiments andapplications of the present teachings, reference is made to theaccompanying drawings that form a part hereof, and in which is shown byway of illustration specific embodiments in which the invention may bepracticed. It is to be understood that other embodiments may be utilizedand changes may be made without departing from the scope of the presentteachings.

Various inventive features are described below that can each be usedindependently of one another or in combination with other features. Forpurposes of better understanding of the present teachings and in no waylimiting the scope of the teachings, it will be clear to one of skill inthe art that the use of the singular includes the plural unlessspecifically stated otherwise. Therefore, the terms “a”, “an”, and “atleast one” are used interchangeably in this application.

A front view of an exemplary embodiment of an apparatus 100 that can beused for continuous curing of a plurality of extruded strands 105 isillustrated in FIG. 1. The apparatus 100 comprises a rigid framestructure 110 formed by interconnecting a plurality of rigid framemembers 115. The rigid frame structure 110 has a top portion 120, abottom portion 125, side portions 130, a front portion 135 and a rearportion 140 (FIG. 6). A rigid top plate member 145 is attached to anupper part of the front portion 135 and a rigid bottom plate member 150is attached to a lower part of the front portion 135. A plurality ofupper spindle units 155 is rotatably attached to the rigid top platemember 145 and a plurality of lower spindle units 160 is rotatablyattached to the rigid bottom plate member 150. A pair of drive motors165 is attached to the rigid frame structure 110. A gear assembly 170attached to the rigid frame structure 110 is operably engaged to thepair of drive motors 165 and a chamber 175 (FIG. 6) is supported on therigid frame structure 110 for curing the plurality of extruded strands105. The plurality of upper spindle units 155 and the plurality of lowerspindle units 160 may include at least a top row of rollers and a bottomrow of rollers. The top row of rollers may be arranged to be verticallystaggered in relationship to the bottom row of rollers.

FIG. 2 illustrates a front view of the apparatus 100 for continuouscuring of a plurality of extruded strands 105 in accordance with thepreferred embodiment of the present invention. The plurality of rigidframe members 115 is interconnected by any mechanical means of welding,riveting etc. to support the rigid frame structure 110. The bottomportion 125 of the rigid frame structure 110 fabricated to rest onground surface for keeping the apparatus 100 in an upright position. Therigid top plate member 145 is attached to an upper part of the frontportion 135. The rigid top plate member 145 is attached, to the frontportion 135 of the rigid frame structure 110 by mechanical means.Similarly the rigid bottom plate member 150 attached to a lower part ofthe front portion 135 fixed to the rigid frame structure 110 bymechanical means. The plurality of upper spindle units 155 is rotatablyattached to the rigid top plate member 145. The plurality of upperspindle units 155 is aligned along two lines on the rigid top platemember 145. The plurality of upper spindle units 155 is positioned atspecific distances along a top line and a bottom line on the rigid topplate member 145. The plurality of upper spindle units 155 arrangedalong the top line and the bottom line are substantially parallel toeach other but each of the adjacent top and bottom plurality of upperspindle units 155 do not lay along the same vertical line. Similarly,the plurality of lower spindle units 160 is positioned at specificdistances along an upper line and a lower line on the rigid bottom platemember 150. The plurality of lower spindle units 160 arranged along theupper line and the lower line are substantially parallel to each otherbut each of the adjacent upper and lower plurality of lower spindleunits 160 do not lay along the same vertical line. Each of the pluralityof lower spindle units 160 positioned on the rigid bottom plate member150 aligns vertically with each of the plurality of upper spindle units155 positioned on the rigid top plate member 145. This causes theplurality of extruded strands 105 to string up in a vertical fashionbetween the plurality of lower spindle units 160 and the plurality ofupper spindle units 155, as shown in FIGS. 1 and 6.

FIG. 3 illustrates a perspective view of the rigid to plate member 145showing the plurality of upper spindle units 155. The rigid top platemember 145 may be made of sheet metal or any other rigid sheet ofmaterial. The rigid top plate member 145 attached to the rigid framestructure 110 is adapted to receive the plurality of upper spindle units155 and the plurality of lower spindle units 160 are rotatably attachedto the rigid top plate member 145 and the rigid bottom plate member 150respectively. Each of the plurality of upper spindle units 155 and theplurality of lower spindle units 160 are provided with a dual spindle towind and unwind the plurality of extruded strands 105. FIG. 3 also showsthe central shaft 180 around which the plurality of upper spindle units155 are placed. The central shaft 180 is rotatably attached with therigid top plate member 145 and the rigid bottom plate member 150. Thedual spindle of each of the plurality of upper spindle units 155 and theplurality of lower spindle units 160 includes a free spinning roller 195and a driven roller 200. The plurality of free spinning rollers 195 isfreely rotatable about the central shaft 180 and the plurality of drivenrollers 200 is keyed to the central shaft 180 and rotates along with thecentral shaft 180. The plurality of extruded strands 105 is wrappedaround the plurality of dual spindle units 230 in a serial manner tomanage a significant amount of length of the plurality of extrudedstrands 105 in a small, compact space.

FIG. 4 illustrates a perspective view of the apparatus 100 showing thepair of drive motors 165, the top gear box 220 and the bottom gear box225. The pair of drive motors 165 is fixed to the rigid frame structure110 and is rotatably engaged with the top gear box 220 and the bottomgear box 225. The pair of drive motors 165 drives the plurality of upperspindle units 155 arranged along two rows on the rigid top plate member145. The top gear box 220 includes a sprocket 210 and a chain 215connecting the sprocket 210 to rotate the plurality of upper spindleunits 155 positioned along the top line on the rigid top plate member145. Similarly the bottom gear box 225 includes a sprocket 210 and achain 215 connecting the sprocket 210 to rotate the plurality of upperspindle units 155 positioned along the bottom line on the rigid topplate member 145. The continuous curing and post-curing apparatus 100allows the extrudate to pass through the plurality of upper spindleunits 155 and the plurality of lower spindle units 160 where theextrudate can be cured and/or post-cured continuously. The continuouscuring and post-curing apparatus 100 allows multiple lines of theplurality of extruded strands 105 a, 105 b to pass through at variousdefined rates decided by a controller (not shown) which controls thespeed of the pair of drive motors 165, causing no disruption in thecuring and/or post-curing process. Multiple lines of the plurality ofextruded strands 105 a, 105 b can be passed at different rates by thecombination of a driven roller 200 fixed to the central shaft 180 andthe free spinning roller 195 on the same central shaft 180 while otherdriven rollers 200 are the opposite configuration allowing for multiplelines that can run at spate speeds while simultaneously passing throughthe same heating/cooling chamber 175. The plurality of upper spindleunits 155 and the plurality of lower spindle units 160 are arranged soas to allow extrudate to string up in a vertical fashion where at theend of each vertical length the extrudate wraps around the driven roller200 or free spinning roller 195 and runs parallel to the extrudate nextto it and wraps around the next spindle and continues this arrangementin series. This allows for a significant amount of linear length to passthrough in a small space and allows the extrudate to remain in theheating and/or the cooling zone for a desired time while remaining acontinuous process. It will be appreciated by a person skilled in theart that a plurality of spindle units may not only be connected inseries, as described above, but also in parallel or in a combination ofin-series and in-parallel.

It should be understood that the plurality of upper spindle units 155and the plurality of lower spindle units 160 depicted in FIGS. 1-4 and 6are exemplary only and those having ordinary skill in the art wouldappreciate that a variety of structures having differing configurationsand numbers (e.g., other than 2) may be substituted for or used inconjunction with the plurality of upper spindle units 155 and theplurality of lower spindle units 160. The plurality of spindle units mayinclude spindle units of the same or differing configurations.

The apparatus 100 and method is configured to allow for multiple ordifferent curing and post-curing dwell times at temperature, based onthe potential varied requirements of the extrudate material. This can bedone by different sized rollers to allow for different size extrudatesand by varying the speed of one or both of the pair of drive motors 165,which are controlled by the controller. The controller can include acentral processing unit for receiving at least one electronic inputsignal and for generating at least one processed electronic outputsignal in accordance with a control program stored in memory. Thecontroller can be programmed to control operating parameters such as thetemperature, dwell time drive motor speed, and the high velocity heat orforced air convection and cooling implemented by the plurality ofheat-exchanger coils. By way of example, and not limitation, sensorssuch as temperature sensors, humidity sensors, and/or position sensorscan provide a signal to the controller or central processing unit toenable accurate adjustment and control of the operating parameters.

FIG. 5 illustrates an exploded view of an exemplary embodiment of a topdual spindle and central shaft assembly 182 a and a bottom dual spindleand central shaft assembly 182 b. Both the top 182 a and the bottom 182b assemblies comprise a dual spindle that includes a free spinningroller 195 and a driven roller 200 positioned around the central shaft180. The free spinning roller 195 is freely rotatable about the centralshaft 180 and the plurality of driven rollers 200 is keyed to thecentral shaft 180 and rotates along with the central shaft 180. Each ofthe driven rollers 200 is keyed to the front end 185 of the centralshaft by means of a collar 205. The rear end 190 of each of the centralshaft 180 is attached with the sprocket 210. The plurality of sprockets210 attached to the rear end 190 of each of the central shaft 180 of theplurality of upper spindle units 155 of the top assembly 182 apositioned along the top line is connected to the top gear box 220 usingthe chain 215 and the plurality of upper spindle units 155 positionedalong the bottom line is connected to the bottom gear box 225. The pairof drive motors 165 independently rotates the plurality of upper spindleunits 155 arranged on a top line and the plurality of upper spindleunits 155 of the bottom assembly 182 b arranged on a bottom line. A pairof separators 235 for positioning each of the central shafts 180 isattached to the rear end 190.

FIG. 6 illustrates a perspective view of the apparatus 100 forcontinuous curing of a plurality of extruded strands 105 in accordancewith the preferred embodiment of the present invention. The chamber 175supported on the rigid frame structure 110 may act as a dual functionchamber for heating/cooling the plurality of extruded strands 105. Thechamber 175 includes a plurality of fined coils (not shown) to act as aplurality of heat-exchange coils. The pair of drive motors 165, whichare controlled by the controller (not shown), drives multiple lines ofthe plurality of extruded strands 105 to pass through the free spinningroller 195 and the driven roller 200. Each of these plurality ofextruded strands 105 run parallel in a vertical fashion between theplurality of upper spindle units 155 and the plurality of lower spindleunits 160. The free spinning roller 195 and the driven roller 200 mayrotate in an opposite configuration allowing multiple lines of theplurality of extruded strands 105 to run at spate speeds. This enablesthe plurality of extruded strands 105 to pass through the chamber 175.The chamber 175 allows continuous heating of the plurality of extrudedstrands 105 by forced air convection process and cooling by utilizingthe plurality of heat-exchange coils. The apparatus 100 cures andpost-cures the extrudate by a method of high velocity heat or forced-airconvection concentrated around the extrudate and also cool the extrudatein the same fashion as heating via heat-exchanger coils in the passageway of the forced air convection where forced air is passed through thefined coils of the heat exchanger and closed looped refrigeration ispassed through the fined coils to chill the forced air to a desiredtemperature.

FIG. 7 illustrates the operational flow chart of a method for continuouscuring and post-curing of the plurality of extruded strands utilizingthe apparatus in accordance with the present teachings. Multiple linesof the plurality of extruded strands are passed through a free spinningroller and a driven roller of each of a plurality of spindle units asindicated at block 250. The plurality of extruded strands is wrappedaround the free spinning roller and the driven roller as indicated atblock 255. Thereafter, a pair of drive motors is started for rotatingthe plurality of spindle units as shown in block 260. The plurality ofextruded strands is then allowed to pass through a dual function chamberthe heating/cooling at a speed determined by a controller (not shown)which controls the speed of the pair of drive motors as indicated atblock 265. Following this, as shown in block 270, the plurality ofextruded strands is allowed to remain in heat/cool exerted by the dualfunction chamber for a predetermined period of time. For achieving thedesired level of curing for the plurality of extruded strands, the steps265 and 270 are repeated which would result in a continuous process ofcuring of the plurality of extruded strands as indicated at block 275.

The apparatus 100 and method cures and post-cures extrudate by themethod of high velocity heat or forced-air convection concentratedaround the extrudate and also can cool the extrudate in the same fashionas heating it via heat-exchange coils in the passage way of the forcedair convection where the forced air is passed through the fined coils(not shown) of the heat exchanger and closed looped refrigeration ispassed through the fined coils to chill the forced air to a desiredtemperature. This apparatus 100 and method also de-humidifies theextrudate by sensing the humidity within a forced air convection chamberand when there is too much humidity the controller (not shown) activatesthe low dew-point air, which is injected into the forced air convectionchamber and vents out the most humid air based on the location ofvent(s) in the system and lowers the humidity to a desired level whichin turn lowers the humidity of the product.

The foregoing description of the preferred embodiment of the presentinvention has been presented for the purpose of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise form disclosed. Many modifications andvariations are possible in light of the above teachings. It is intendedthat the scope of the present invention not be limited by this detaileddescription, but by the claims and the equivalents to the claimsappended hereto.

1. An apparatus for continuous curing of a plurality of extruded strandscomprising: a rigid frame structure formed by interconnecting aplurality of rigid frame members, the rigid frame has a top portion, abottom portion, a pair of side portions, a front portion and a rearportion; a rigid top plate member attached to an upper part of the frontportion; a rigid bottom plate member attached to a lower part of thefront portion; a plurality of upper spindle units rotatably attached tothe rigid top plate member; a plurality of lower spindle units rotatablyattached to the rigid bottom plate member; a plurality of dual spindlesprovided in the plurality of upper spindle units and the plurality oflower spindle units, wherein each dual spindle comprises a free spinningroller and a driven roller, and arranged in the plurality of upperspindle units and the plurality of lower spindle units such that a nextdual spindle has a configuration opposite a prior dual spindle, aplurality of drive motors attached to the rigid frame structure; a gearassembly operably engaged to the plurality of drive motors, the gearassembly being attached to the rigid frame structure; and a chambersupported on the rigid frame structure, the chamber comprises a dualfunction chamber configured for heating and cooling; wherein theplurality of drive motors drives the gear assembly to continuouslytransfer a plurality of extruded strands between the plurality of upperspindle units and the plurality of lower spindle units such that theplurality of extruded strands string up in a vertical fashion thatcontinuously alternates between the plurality of lower spindle units andthe plurality of upper spindle units and continuously passes through thechamber for continuous curing and post-curing and the plurality of drivemotors drive the gear assembly such that each of the drive motors isoperated independently of the other to independently control transfer ofeach plurality of extruded.
 2. The apparatus of claim 1 wherein each ofthe plurality of lower spindle units aligns vertically with each of theplurality of upper spindle units.
 3. The apparatus of claim 1 whereineach of the plurality of extruded strands between the plurality of lowerspindle units and the plurality of upper spindle units run parallel toeach other.
 4. The apparatus of claim 1 wherein the plurality of lowerspindle units is positioned at specific distances along an upper lineand a lower line on the rigid bottom plate member and wherein theplurality of upper spindle units are positioned at specific distancesalong a top line and a bottom line on the rigid top plate member.
 5. Theapparatus of claim 4 wherein the upper line and lower line arevertically staggered to each other and the top line and the bottom lineare vertically staggered to each other.
 6. The apparatus of claim 1wherein each of the plurality of lower spindle units and the pluralityof upper spindle units is rotatable about a central shaft having a frontend and a rear end.
 7. The apparatus of claim 6 wherein the centralshaft is rotatably attached to the rigid top plate member and the rigidbottom plate member.
 8. The apparatus of claim 7 wherein each of aplurality of driven rollers is keyed to the front end of the centralshaft by means of a collar.
 9. The apparatus of claim 8 wherein each ofa plurality of free spinning rollers is freely rotatable about thecentral shaft.
 10. The apparatus of claim 9 wherein the rear end of eachof the central shafts is attached with a sprocket.
 11. The apparatus ofclaim 10 wherein each of the sprockets arranged along the top line isoperatively connected to one of the plurality of drive motors using achain to form a top gear box and wherein each of the sprockets arrangedalong the bottom line is operatively connected to another of theplurality of drive motors using a chain to form a bottom gear box. 12.The apparatus of claim 11 wherein the plurality of drive motors isengaged with the top gear box and the bottom gear box to rotate theplurality of upper spindle units.
 13. The apparatus of claim 1 whereinthe dual function chamber allows continuous heating of the plurality ofextruded strands by forced air convection process and cooling byutilizing a plurality of heat-exchange coils.